The present invention relates to a laser writing device for image forming equipment of the type using an electrophotographic procedure and, more particularly, to a laser writing device capable of producing high quality images by reducing irregularities in writing position.
A laser writing device is one of conventional image writing devices applicable to the above-mentioned type of image forming equipment. A laser printer, for example, belongs to a family of image forming equipment implemented with a laser writing device. Specifically, a conventional laser printer has a single polygonal mirror for steering two independent laser beams. The two laser beams steered by the polygonal mirror each is routed through a particular f-theta lens and a plurality of successive mirrors to reach a particular position on an image carrier which is implemented as a photoconductive element. As a result, latent images are electrostatically formed on different positions of the photoconductive element. The problem with such a conventional laser writing device is as follows. Assume that the configuration of the mirror surfaces of the polygonal mirror is inaccurate, i.e., each reflecting surface of the mirror is inclined and cannot reflect the incident laser beam in an expected direction, or that the rotation of the polygonal mirror is not stable due to eccentricity, for example. Then, the positions on the photoconductive element to which the scanning beams are incident, i.e., writing positions are deviated to affect the quality of resultant images critically.